Flat color television tube having plurality of mirror deflection systems

ABSTRACT

An electron discharge tube for the display of luminous color images including a tube envelope having a picture screen electrode disposed adjacent to the viewing surface thereof. The picture screen electrode has a plurality of luminous strips arranged substantially parallel to one another. A pair of grids are arranged behind the picture screen electrode and a recoil electrode is spaced behind the pair of grids. The first of the pair of grids consists of a plurality of narrow parallel strips sloping against the picture screen electrode. The electron beam is directed into the space between the picture screen electrode and the recoil electrode in a direction generally away from the picture screen electrode. The potential of the recoil electrode reverses the direction of the beam toward the picture screen electrode and through the pair of grids.

BIB-W221 OR 396219319 .l..l.".i.b""/J. UK 3596119519 [72] Inventors Hinrich Heynisch [56] References Cited Graefeifing; UNITED STATES PATENTS Hannjiirg Bittorf, Munich; Werner Veith,

2,650,264 8/1953 We|mer.... 313/925 Munich, all of Germany 2,926,274 2/1960 Gabor 313/77 [21] Appl. No. 740,329

. 2,999,957 9/1961 Schagen et al. 313/80 X [22] Filed June 26, 1968 3,041,489 6/1962 Velth 313/77 X [45] Patented Nov. 16, 1971 [73] Assignee Priming Developments Inc 3,064,154 11/1962 Law 313/80 X Rockefeller Gem", NY. 3,412,282 11/1968 Lord et a1. 313/80 X [32] Priority June 27, 1967 Primary Examiner-Robert Sega] [33] Germany Attorney-HilL Shennan, Meroni, Gross & Simpson [31] S I 10520 ABSTRACT: An electron discharge tube for the display of luminous color imagesincluding a tube envelope having a picture screen electrode disposed adjacent to the viewing surface thereof. The picture screen electrode has a plurality of luminous strips arranged substantially parallel to one another A 54] FLAT COLOR TELEVISION TUBE HAVING pair of grids are arranged behind the picture screen electrode PLURALI'I'Y 0F MIRROR DEFLECTION SYSTEMS 5 Claims, 3 Drawing Figs.

u.s. Cl 313/77, 313/73 rm. Cl ..1-101j 29/74, H01 j 29/80, H01 j 3 1/20 me of Search 313/77, 76, so

and a recoil electrode is spaced behind the pair of grids. The first of the pair of grids consists of a plurality of narrow parallel strips sloping against the picture screen electrode. The electron beam is directed into the space between the picture screen electrode and the recoil electrode in a direction generally away from the picture screen electrode. The potential of the recoil electrode reverses the direction of the beam toward the picture screen electrode and through the pair of grids.

.............--.-.......-......................L.......-.j................, 5 \\\\\\|J FLAT COLOR TELEVISION TUBE HAVING PLURALITY OF MIRROR DEFLECTION SYSTEMS BACKGROUND OF THE INVENTION Field of the Invention The field of art to which this invention pertains is a cathoderay tube for the reproduction of color images and in particular to a cathode-ray tube having a plurality of color stripes as the image reproducing means.

SUMMARY OF THE INVENTION It is an important feature of the present invention to provide an improved cathode-ray tube for the reproduction of color images.

It is another feature of the present invention to provide a cathode-ray tube which utilizes color stripes as a luminous image-reproducing means.

It is an object of the present invention to provide a means for impinging an electron beam at a substantially constant angle on to a surface of a picture screen electrode of a cathode-ray tube.

It is also an object of this invention to provide a cathode-ray tube having a picture screen electrode, a pair of grids immediately adjacentthereto, a recoil electrode spaced substantially behind the pair of grids and a means for introducing a cathode-ray beam into the space between the pair of grids and the recoil electrode in such a way as to causethe beam to impact at a uniform angle against the picture screen electrode.

These and other objects, features and advantages of the present invention will be understood in greater detail from the following description of the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross section of a flat picture tube described above;

FIGS. 2 and 3 show the path of associated beams.

DESCRIPTION OF THE PREFERRED EMBODIMENT The invention pertains to an electron beam tube having only one electronic beam for the reproduction of colored television images on a picture screen having at least two luminous substances of elementary groups and having two grids arranged ahead thereof. These grids have such potentials that in the range of one grid (the color control grid) braked electrons of some 100 volts are present. The color control grid is in the form of narrow parallel metal strips sloping against the screen electrode normal line. The other grid is arranged ahead of the color control grid as a potential plane grid and consists of a mesh grid of any structure. The elementary groups of the picture screen consist of luminous stripes extending parallel to the metal bands or slats of the color control grid.

As is known, in such a tube the color selection takes place by individual cylindrical lenses formed in the range of the color control grid. In view of the possibly unfavorable capacitive influence of the grid electrode, the color control voltage is thereby applied jointly, for example to the color control grid, the potential grid and perhaps also to the picture screen electrode. The constant impact angle absolutely indispensable for color control in the prior art is 90. As is known, the maintenance of such a 90 requirement over the entire picture screen causes considerable difliculties. On the other hand, if this angle is not maintained precisely there will be considerable color errors.

In the picture tube according to prior art, depending on whether the potential of the color control grid is selected negative or positive in relation to the cathode potential, there will be interference either due to inevitable lens errors or there will be background illumination due to secondary electrons arriving on the picture screen electrode.

A certain remedy was achieved by simple or multiple bending of the metal bands or slats perhaps into the shape of a shovel. This measure made is possible, among other things, to

eliminate the structure of equal graduation per se of the potential plane grid which in the manufacture of the tube represents considerable difficulty. However, this advantage was not without a sacrifice in the precision of the color selection process. Therefore the design of the potential grid even as a grid with a limiting aperture of correspondingly identical structure offered an improvement in color control quality, but not without a considerable reduction in the degree of effectiveness, that is of the yield and thus of the brightness.

The present invention resolves the above-reported difiiculties in maintaining a constant impact angle of the electron ray by designing the discharge vessel as a flat picture tube having certain electron optic features connected therewith.

' This is accomplished in an electron tube with only one electron ray and by designing the discharge vessel as a flat picture tube and by the application of known counterfield focusing in the case of an electron ray shot obliquely into the transverse field of a plate condenser from the color control grid. The metal bands are inclined 45 against the end of the grid electrode at which the ingress of the clustered electron ray takes place 45 against a recoil electrode arranged at sufficient distance from the potential grid by means of a slot aperture system (collimator system) located in the plane of the potential grid. Such a measure offers considerable advantages. As a result of the counterfield focusing, the impact angle for the electron ray beam-at 45 slope remains constant over the entire beam width. However, the focusing achieved thereby, and thus the resolution governing the quality of the image, are independent in a first approximation of the beam width, that is the line length. Hence, it is only necessary that there be a correspondingly deflected cluster of electron beams in the direction of the lines through a longitudinal slot extended perpendicularly to the direction of the lines with a slop of 45 in the condenser area formed by the' potential grid and the cor responding counterelectrode. This is accomplished with particular advantage in that the electron beam is deflected approximately immediately prior to the collimator system by 135 with the aid of a deflector electrode. This would require a generator system laterally from the picture with a system axis oriented vertically to the picture screen electrode. By means of an additional preceding deflection by likewise with a deflector electrode, particularly a deflection plate, the axis of the system for generating the electron beams may 'extend parallel to the picture screen electrode. In this regar'd'it isadvantageous to provide one joint counter electrode for both deflection plates. These measures ofl'er adequate space along the path of the beams for two installations which focus independently in two directions perpendicular to each other and for a linear deflection installation for the deflection of the image.

Additional details of the invention will be explained by means of an embodiment shown schematically in the drawings.

In FIG. 1, an electron gun I generates an electron beam 2, which extends parallel to a potential grid 3. Focusing installations 4 and 5 focus independently of each other in two mutually perpendicular directions. A linear deflection system 6 is provided for image deflection. This system is energized with sawtooth voltage. In its further path the electron beam is first deflected at a deflection electrode 9 by 90 and subsequently at an additional deflection electrode 10 by I35", a total of 225. Such a deflection angle would also be possible in a single operation in a corresponding cylindrical condenser.

Due to the fact that focusing automatically occurs with the deflection, the deflected and already prefocused electron beam passes under a defined angle thru a focal system 7,8 (collimator system). This system includes at least two longitudinal slots extending perpendicularly to the line direction in each case and thus enters the reversing or focusing area. Electrode 11 extending substantially perpendicularly to the potential grid and provided as a joint counterelectrode for the two deflection plates 9 and 10 is used simultaneously as a screen for the electron beam against the deflection plate condenser area. The electrode 11 has a relatively high positive potential.

The image deflection system 6 which may consist of a pair of panels deflects the beam out of the plane of the drawing. When using a deflection panel 9 tilted under 45 for the first deflection operation, a sequence of electron beams extending over the center line of a cylinder is produced at the image deflection installation 6 after reflection of the electrons at the plate during the passage of the image sawtooth voltages therethrough.

In order for a marginal ray 13 to be reflected following reflection at reflector in the same plane 14 as a central ray 12, the deflection plate 10 must be twisted, that is to say curved accordingly. A sequence of parallel rays, all of which enter the reflector (reversing) area precisely at 45, is then produced behind the collimating slots as the sawtooth voltage passes therethrough. The amperage of the electron beam is thereby highly overdimensioned, that is, it is so selected that following the scattering of the ray 14 at the focal points 7 and 8 of the collimator system, a still adequate current is available.

The electron beam entering the reflector and reversing area formed by electrodes 3 and 15 is bent back, depending on the momentary countervoltage of the counterelectrode 15 over a very short or a very long path 16 or 17 respectively to the potential grid 3 in order to enter the color control grid and to impact upon the screen electrode 21 with its luminous color strips. The distance between the terminal points of impact 18 and 19 is thereby equal to the length of a line and thus approximately equal to the television image width. Thus the line deflection takes place in a type of counterfield focusing by means of a sawtooth voltage applied between potential grid 3 and recoil electrode 15, while the deflection of the image is accomplished by a linear electrostatic deflection system 6.

The means 4 and 5 for separate focusing in two directions perpendicular to each other are very diverse in their effect. While for focusing in one direction, namely parallel to the surface of the drawing, an additional deflective focusing will occur in both deflection plates 9 and 10; the means provided at the input accordingly only needs to supply a prefocusing. In the cylindrical lens provided for the other direction, on the other hand, a precision adjustment of the type of a dynamic focusing is carried out in view of the electron paths of diverse lengths until impact upon points 18 and 19. The individual beams leaving the collimator system 7 and 8 as a band beam extending parallel are thus focused only upon impact upon the image screen as a result of the focusing effect of the cylindrical lens 4 onto one point. As a result of this flat image focusing the ingress angle of the electron beam into the reflector area (condenser area) is maintained very nearly constant for the entire image height. This in turn makes it possible for the entire plane image surface to be scanned with an approximately unifonn sharpness.

FIG. 2 shows schematically the possible splitting of the electron beam in the color control grid when the three colors are generated. After passing thru the potential grid 3, the electrons impact upon the color control grid 20 and afterwards upon the luminous screen electrode 21, whose elementary groups consist in each case of at least two and here three color strips (r,b,g) extending parallel to the color control grid.

In the simplest case the potential grid 3 comprises a woven mesh screen whose grid constant is in no connection with the grid constant of the color control grid 20. Its only task is to determine the potential of the electrons after reversal in the reflector area and to see that neat plane potential surfaces are produced in said reversing area. its potential preferably corresponds with that of the second collimator slot, that is approximately 3000-4000 volts. The potential of the color control grid is some 100 volts above that of the cathode potential so that during color control operation zero volts is not reached. This makes possible the use of the entire aperture of the color control grid for the cross section of the electron ray without the occurrence of too great aberration errors at the edge of the individual lenses.

These individual lenses are formed by the three adjacent electrodes, namely the potential grid 3, the color control grid 20 and the luminous screen electrode 21. The color control grid has the lowest potential of these three electrodes, namely some volts in relation to the cathode potential, while the luminous screen electrode has the highest positive potential in order to achieve as high a conversion of the electron energy into light.

As a result of such an asymmetry in the distribution of the voltage a potential picture is created according to the potential lines drawn in FIG. 2. The fact that these potential lines are curved more near potential grid develops a cluster of electron rays 22,23 which is too wide to be segregated into two partial rays without the grid electrode absorbing an essential part of the electron ray. The electron rays 24 and 25 produced by the splitting impact on the image screen electrode 21 upon corresponding luminous strips 26 and 27, both of which light up with the same color.

In the distribution of potential shown, it is possible to tension individual thin wires 28 at major distances over the color control grid. The wires 28 prevent oscillations of the color control strips against each other in case of mechanical vibrations. For this purpose sufficiently thin wires, the like of which are known from tension grids, are selected, so that the potential image is not disturbed. in other words, these wires do not make themselves noticeable in a disturbing manner on the image screen.

When the potential of the color control grid is varied, a shifting of the electron beam in relation to the choice of color is accomplished with high frequency, as can be generated in the simplest case by superimposing the auxiliary color carrier frequency on the first harmonic of the beam. The electron beam 22 passing thru the potential grid 3 and subsequently thru the color control grid 20, impacts as beam 29 upon the image screen electrode 21, and on a luminous strip 21. The beam is deflected by reducing the voltage at the color control grid into beam 30 upon another luminous strip 6. The voltage variation required for color control is in the order of 100 volts.

Such a shifting can be accomplished by varying the DC voltage in order to correct the color of the image in a simple manner, so that a special coordination of the luminous strips with the color control slats, which is difficult, is unnecessary.

The following advantages are obtained by the flat image and counterfield focusing over the color control colored picture tubes known in the prior art. The incoming and/or impact angle of 45 at the color control grid is assured over the entire image surface. Although the color control grid must be produced precisely and with a low tolerance, a dotlike coordination of the luminous stripe in relation to the gaps of the color control grid as in a masked tube is unnecessary. lt sufflces for the structures of the color strips and the color control grid to be equal and to adjust both electrodes parallel to each other. An exact coordination of the individual colors in their relative position with respect to the color control grid is un necessary because the ray can be shifted easily by variations in the DC bias at the color control grid. increased mechanical stability can be accomplished by noninterfering thin tension wires. The capacity applicable between potential grid and color control grid can be maintained correspondingly low, in contrast to other tubes known from prior art by maintaining sufiiciently large distance therebetween. Furthermore, the control effect is increased over the color picture tube known under the name chromatron, due to the fact that the color selection grid is at lowest potential so that secondary electrons possibly generated can be aspirated off by the potential grid without reaching the image screen. In addition the color sequency of the luminous strips is cyclical and not alternating. A reduction of the assent of the color control grid for an increased release does not cause a corresponding increase of the control capacity. The tube is appropriate both for in-line direction and in perpendicular direction thereto to achieve approximately the complete black-white resolution providing the structure of the color control grid is sufficiently fine.

The invention claimed is:

1. An electron radiation tube having a source for generating one electron beam for the reproduction of color television images, one picture screen electrode having at least two fluorescent substances of different color-emitting characteristics thereon, said beam source being arranged in said tube to direct the electron beam in an initial direction substantially parallel to said picture screen electrode means for deflecting said beam, a first electrode for rotating the affected beam through an angle of substantially 90, a second electrode for rotating the beam through a further angle of substantially greater than 90 into a path with is directed generally away from the picture screen electrode, a recoil electrode spaced from the picture screen electrode for redirecting the beam generally toward said picture screen electrode, two grids arranged adjacent to said screen and means for applying such potentials to said grids so that in the range of one of said grids decelerated electrons of approximately 100 volts are present, one of said grids being a color control grid consisting of narrow parallel metal strips disposed at an angle to the picture screen, the other grid being arranged adjacent said color control grid oppositely of said screen and consisting of a mesh structure, the fluorescent substances of the picture screen electrode consisting of strips extending parallel to the metal strips of the color control grid, said tube having a relatively flat envelope and having a counterfield focusing electrode, the metal strips of the color control grid being inclined at substantially 45 with respect to the picture screen through which said beam passes.

2. An electron discharge device comprising a tube envelope having a picture screen electrode disposed adjacent to a viewing surface thereof, said picture screen electrode having a plurality of stripes of different color emitting fluorescent substances arranged substantially parallel to one another along the surface thereof, a color control grid structure arranged in a plane substantially parallel to and ahead said picture screen, said color control grid including a plurality of relatively narrow substantially parallel strips sloping against the picture screen electrode and being substantially parallel to the color stripes thereof, a grid arranged in a plane immediately ahead and substantially parallel to said color control grid, a source for generating an electron beam in said tube initially in a direction generally parallel to said picture screen electrode, a first electrode for rotating the beam through an angle of substantially a second electrode for rotating the beam through a further angle of substantially greater than 90 into a path which is directed generally away from the picture screen electrode, a recoil electrode spaced from the picture screen electrode for redirecting the beam generally toward said picture screen electrode, first beam deflection means located between said beam source and said first electrode, and means for varying the voltage on said recoil electrode to cause a second deflection of said beam, whereby said beam is caused to scan said picture screen.

3. An electron discharge device in accordance with claim No. 2 wherein the angle of ingress against said recoil electrode is 45".

4. An electron discharge device in accordance with claim No. 2 wherein said parallel strips slope at approximately 45 relative to said picture screen.

5. An electron discharge device in accordance with claim No. 1 wherein the system axis of the generating means for the electron beam extends parallel to the direction of the recoil electrode. 

1. An electron radiation tube having a source for generating one electron beam for the reproduction of color television images, one picture screen electrode having at least two fluorescent substances of different color-emitting characteristics thereon, said beam source being arranged in said tube to direct the electron beam in an initial direction substantially parallel to said picture screen electrode means for deflecting said beam, a first electrode for rotating the affected beam through an angle of substantially 90*, a second electrode for rotating the beam through a further angle of substantially greater than 90* into a path with is directed generally away from the picture screen electrode, a recoil electrode spaced from the picture screen electrode for redirecting the beam generally toward said picture screen electrode, two grids arranged adjacent to said screen and means for applying such potentials to said grids so that in the range of one of said grids decelerated electrons of approximately 100 volts are present, one of said grids being a color control grid consisting of narrow parallel metal strips disposed at an angle to the picture screen, the other grid being arranged adjacent said color control grid oppositely of said screen and consisting of a mesh structure, the fluorescent substances of the picture screen electrode consisting of strips extending parallel to the metal strips of the color control grid, said tube having a relatively flat envelope and having a Counterfield focusing electrode, the metal strips of the color control grid being inclined at substantially 45* with respect to the picture screen through which said beam passes.
 2. An electron discharge device comprising a tube envelope having a picture screen electrode disposed adjacent to a viewing surface thereof, said picture screen electrode having a plurality of stripes of different color emitting fluorescent substances arranged substantially parallel to one another along the surface thereof, a color control grid structure arranged in a plane substantially parallel to and ahead said picture screen, said color control grid including a plurality of relatively narrow substantially parallel strips sloping against the picture screen electrode and being substantially parallel to the color stripes thereof, a grid arranged in a plane immediately ahead and substantially parallel to said color control grid, a source for generating an electron beam in said tube initially in a direction generally parallel to said picture screen electrode, a first electrode for rotating the beam through an angle of substantially 90*, a second electrode for rotating the beam through a further angle of substantially greater than 90* into a path which is directed generally away from the picture screen electrode, a recoil electrode spaced from the picture screen electrode for redirecting the beam generally toward said picture screen electrode, first beam deflection means located between said beam source and said first electrode, and means for varying the voltage on said recoil electrode to cause a second deflection of said beam, whereby said beam is caused to scan said picture screen.
 3. An electron discharge device in accordance with claim No. 2 wherein the angle of ingress against said recoil electrode is 45*.
 4. An electron discharge device in accordance with claim No. 2 wherein said parallel strips slope at approximately 45* relative to said picture screen.
 5. An electron discharge device in accordance with claim No. 1 wherein the system axis of the generating means for the electron beam extends parallel to the direction of the recoil electrode. 